CD8A and infection: CD8+ T cell response against the BA.2 antigen was significantly associated with age (OR = 1.03, 95% CI 1.01–1.05) and anti-N IgM (OR = 5.51, 95% CI 1.92–25.5), and significantly inversely associated with the time elapsed since the last vaccine dose or infection (OR = 0.89, 95% CI 0.81–0.99).